Presently, an edge finder is typically used by a machinist to find a point on an axis, say an X axis, and then an edge finder is used again to find another point on a second axis, say a Y axis. The intersection of these two axes defines an origin. It is desirable to locate the origin directly, thereby saving the machinist time and otherwise simplifying the process. In addition, a single point direct determination of the origin may be more accurate than two separate edge finder measurements and the required extrapolation to the origin.
U.S. Pat. No. 3,999,299 discloses an edge finder that is still popular today. A rotating cylinder contains an off-axis spring. The visual inspection of cylinder wobble indicates the point where the edge finder touches the part to be machined, thereby determining a point on an axis. It is desirable to minimize the guesswork used for wobble estimation in the process of edge detection. For example, an origin determination may also include an indication that the origin is being approached, and an indication that the origin has been passed, with the inherent option for the machinist to pass by and then return to the right spot at the origin.
U.S. Pat. Nos. 5,272,818 and 5,522,147 disclose calculations and extrapolations to deduce an origin. The patents do not address the concept of right-handed and left-handed origins as being useful to a machinist.
In view of the foregoing, it would be desirable to provide improved techniques for identifying a machine tool origin.